Source of Support: None, Conflict of Interest: None

How to cite this article:
Saha PK, Baur B, Gupta S. Thyroid stimulating hormone measurement as the confirmatory diagnosis of hypothyroidism: A study from a tertiary-care teaching hospital, Kolkatta. Indian J Community Med 2007;32:139-40

Hypothyroidism, the most common functional disorder of thyroid gland is an important public health issue. The condition can be identified by measuring the thyroid stimulating hormone (TSH) concentration in serum, which should be above the reference range of 0.6-5.0 mIU/ml. It may or may not be associated with the decrease in serum free T 4 concentration, these thyroid disorders are known as overt and sub-clinical hypothyroidism, respectively. The present study was designed to estimate the prevalence of hypothyroidism among the suspected cases attending a tertiary-care teaching hospital in Kolkatta.

Materials and Methods

A hospital-based cross-sectional study involving 903 patients (age range, 6-72 years) was conducted in the Department of Biochemistry, Calcutta National Medical College (CNMC), Kolkatta during March 2004 to February 2005. The patients were referred from different out-patient departments of CNMC hospital as suspected cases of hypothyroidism. Data about the patient's age, sex, and clinical symptoms as noted on OPD tickets and information on symptoms confirmed directly by the patient was collected using a pre-tested and pre-designed pro-forma with informed consent from the patient. In case of more than one symptom, the prevailing symptom at the time of admission was taken into account. All the referred symptomatic patients were studied to determine the presence of the disease. This method was employed since there is no single method or combination of methods that can accurately predict the presence of hypothyroidism. Only the biochemical test, namely, measurement of TSH concentration can confirm the diagnosis.[1]

A 5-ml blood sample was collected from each patient after an overnight fast. The serum was used to estimate the TSH levels by using the sandwich enzyme-linked immunosorbent assay kit manufactured by Lilac Medicare (P) Ltd. The serum TSH concentration level greater than 5 µIU/ml was considered abnormal. [2] Third party external quality system traceable to international standards was not available in our set up; this can be considered as a limitation of this study.

Results and Discussion

Out of 903 suspected cases of hypothyroidism, 232 cases were found to be actually suffering from the disease as confirmed by TSH concentration levels; therefore, the prevalence of hypothyroidism was calculated to be 25.7%. Among 232 hypothyroid cases, 181 (78.02%) were females and 51 (21.98%) were males. The age range of the patients was 6-72 years. The maximum number of patients belonged to the age group of 36-45 years with a clear female preponderance. However, the disease was also found to be common in other age groups. Of all cases, 40.5% cases were found to be in the age group of 16-35 years; this demonstrated that hypothyroidism can be observed in the younger generation as well [Table - 1]. This is in accordance with the study on the prevalence of the Colorado thyroid disease involving 25,862 participants. The study showed that 9.5% of the subjects had an under active thyroid (hypothyroidism), and that hypothyroidism was more prevalent in women at the age of 34 years or more. [3]

It is evident from [Table - 2] that women presented with menorrhagia (20%) and infertility as the prevalent symptoms, whereas the men presented with muscle and joint pain (29.6%) and psychiatric problem (29.4%) as the prevalent symptoms. Goiter was a common symptom observed in individuals reaching puberty and in adults (non-puberty goiter). Other common symptoms included maturational delay (observed under 10 years of age), dyspnoea, auditory dysfunction, and chronic ill-health. Bemden et al.[4] observed that the thyroid status could not be predicted from the clinical signs and symptoms in elderly community-dwelling patients. In the present study, it was found that the clinical signs and symptoms widely varied among individuals and were not conclusive for diagnosis of hypothyroidism. This is true even in patients presenting with goiter. As far as puberty goiter was concerned, of the 44 females and 17 males, 24 females and 6 males (49.2%) were found to suffer from hypothyroidism. In cases of non-puberty goiter (F = 68, M = 34), 45.1% cases were found to suffer from the disease [Table - 2].

Hence, no one symptom of hypothyroidism appears to be the main predictor of thyroid failure. The presented symptoms are often vague, develop slowly, and even go unnoticed. Other studies also report that the high prevalence of unrecognized hypothyroidism can be reduced by estimating TSH concentration levels. [5]

Conclusion

From this study, it can be concluded that although hypothyroidism is more prevalent in the age group of 36-45 years, it is also observed in other age groups. Additionally, since different individuals present with varying symptoms, the clinicians cannot rely on the symptoms alone. Furthermore, population screening is expensive and requires a definite policy. Considering all these facts, it can be concluded that the measurement of serum TSH concentration in relevant cases (having suggestive symptoms) is a simpler and practical approach to diagnose hypothyroidism. This test, if necessary, should be followed by the estimation of T 4 concentration . Creating an awareness with regard to these tests at all levels is necessary to overcome the burden and outcome of hypothyroidism.